Fixed Bed

pete57

We are finding the fixed bed in our caravan abit soft due to lack of support to the slats,on our old van there was a support bar in the middle running the length of the bed, can't understand why this is missing on a newer van.I have thought about cutting
a piece of ply to fit over the slats but would this cause the mattress to sweat?Any ideas would be greatfully received.Pete.